Potential of Radio Telescopes as High-Frequency Gravitational Wave Detectors

Area of Science:

• Cosmology
• Astrophysics
• Radio Astronomy

Background:

• Gravitational waves and photons can convert into each other in magnetic fields.
• The cosmic microwave background (CMB) is a relic radiation from the early universe.
• Detecting high-frequency gravitational waves is a significant challenge in modern physics.

Purpose of the Study:

• To investigate the conversion of gravitational waves to photons in magnetic fields.
• To demonstrate how CMB distortions can be used to detect early universe gravitational wave sources.
• To establish new constraints on gravitational wave amplitudes using existing radio astronomy data.

Main Methods:

• Theoretical modeling of gravitational wave-photon conversion in cosmic magnetic fields.
• Analysis of data from radio telescopes like EDGES and ARCADE 2.
• Comparison of observational constraints with theoretical predictions and laboratory limits.

Main Results:

• Cosmic microwave background (CMB) distortions are a consequence of gravitational wave-photon conversion.
• EDGES and ARCADE 2 data provide upper bounds on gravitational wave amplitudes (h_c) in the MHz to GHz range.
• Constraints derived from magnetic fields are significantly stronger than current laboratory limits.

Conclusions:

• The CMB serves as a potential detector for high-frequency gravitational wave sources active before reionization.
• Current radio astronomy measurements already place stringent limits on gravitational wave amplitudes.
• Future 21 cm astronomy could further improve these cosmological constraints on gravitational waves.